A plant compound found in onions, apples and oranges has the potential to save "thousands of lives" by preventing blood clots linked to heart attacks and strokes, say scientists.
Rutin, or quercetin-3-rutinoside, is naturally found in many fruits, vegetables and teas and is also sold as a herbal supplement.
Scientists conducting tests on clot-prone, or thrombotic, mice found that the compound had a powerful effect, preventing clots in arteries and veins.
Study leader Dr Robert Flaumenhaft, from Beth Israel Deaconess Medical Center in Boston, US, said: "Rutin proved to be the most potently anti-thrombotic compound that we ever tested in this model.
"Clots occur in both arteries and in veins. Clots in arteries are platelet-rich, while those in veins are fibrin-rich. This discovery suggests that a single agent can treat and prevent both types of clots."
The research, reported online in the Journal of Clinical Investigation, focused on an enzyme called protein disulphide isomerase (PDI) which is present in all cells. Previous work showed that PDI is rapidly secreted from both platelets, the "clotting bodies" in blood, and cells lining blood vessel walls during clot formation. Inhibiting PDI was found to block thrombosis in mice.
After screening an array of more than 5,000 compounds, the scientists discovered that rutin was the most potent suppressor of PDI associated with clotting. Crucially it was also safe, because it did not interfere with PDI inside cells, where the enzyme is needed for the proper synthesis of proteins.
Dr Flaumenhaft added: "A safe and inexpensive drug that could reduce recurrent clots could help save thousands of lives. These pre-clinical trials provide proof of principle that PDI is an important therapeutic target for anti-thrombotic therapy."
He pointed out that the US Food and Drug Administration (FDA) had already ruled that rutin was safe, paving the way for using it to treat patients.
"We are poised to expeditiously test this idea in a clinical trial, without the time and expense required to establish the safety of a new drug," said Dr Flaumenhaft.